The suspension in the 1951 GMC (or Chevy...same thing) was very basic. Until we get a better idea regarding the questions above, please let me add one specific caution: Over the past 60 years I've seen people lower these by removing leaves from the leaf springs. And I understand...it seems like a logical thought. Each spring has 8 leaves and it seems if you removed maybe 1/2 of them the truck would be lowered. And up to a point that is true. But (there's always a but)...In this style of suspension your front axle attaches only to those 2 leaf springs. Nothing else secures it. So if one of those leaf springs (which is old and has seen decades of use) breaks because it is now over-stressed because it has too few leaves, your axle could suddenly become disconnected and that would be a catastrophic problem.
